Build divdi3 only for architecture that required it

As noted in [1], divdi3 object is only exported in a handful ABIs
(i386, m68k, powerpc32, s390-32, and ia64), however it is built
for all current architectures regardless.

This patch refact the make rules for this object to so only the
aforementioned architectures that actually require it builds it.

Also, to avoid internal PLT calls to the exported symbol from the
module, glibc uses an internal header (symbol-hacks.h) which is
unrequired (and in fact breaks the build for architectures that
intend to get symbol definitions from libgcc.a).  The patch also
changes it to create its own header (divdi3-symbol-hacks.h) and
adjust the architectures that require it accordingly.

I checked the build/check (with run-built-tests=no) on the
following architectures (which I think must cover all supported
ABI/builds) using GCC 6.3:

aarch64-linux-gnu
alpha-linux-gnu
arm-linux-gnueabihf
hppa-linux-gnu
ia64-linux-gnu
m68k-linux-gnu
microblaze-linux-gnu
mips64-n32-linux-gnu
mips-linux-gnu
mips64-linux-gnu
nios2-linux-gnu
powerpc-linux-gnu
powerpc-linux-gnu-power4
powerpc64-linux-gnu
powerpc64le-linux-gnu
s390x-linux-gnu
s390-linux-gnu
sh4-linux-gnu
sh4-linux-gnu-soft
sparc64-linux-gnu
sparcv9-linux-gnu
tilegx-linux-gnu
tilegx-linux-gnu-32
tilepro-linux-gnu
x86_64-linux-gnu
x86_64-linux-gnu-x32
i686-linux-gnu

I only saw one regression on sparcv9-linux-gnu (extra PLT call to
.udiv) which I address in next patch in the set.  It also correctly
build SH with GCC 7.0.1 (without any regression from c89721e25d).

[1] https://sourceware.org/ml/libc-alpha/2017-03/msg00243.html

	* sysdeps/i386/symbol-hacks.h: New file.
	* sysdeps/m68k/symbol-hacks.h: New file.
	* sysdeps/powerpc/powerpc32/symbol-hacks.h: New file.
	* sysdeps/s390/s390-32/symbol-hacks.h: New file.
	* sysdeps/unix/sysv/linux/i386/Makefile
	[$(subdir) = csu] (sysdep_routines): New rule: divdi3 object.
	[$(subdir) = csu] (sysdep-only-routines): Likewise.
	[$(subdir) = csu] (CFLAGS-divdi3.c): Likewise.
	* sysdeps/unix/sysv/linux/m68k/Makefile
	[$(subdir) = csu] (sysdep_routines): Likewise.
	[$(subdir) = csu] (sysdep-only-routines): Likewise.
	[$(subdir) = csu] (CFLAGS-divdi3.c): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/Makefile
	[$(subdir) = csu] (sysdep_routines): Likewise.
	[$(subdir) = csu] (sysdep-only-routines): Likewise.
	[$(subdir) = csu] (CFLAGS-divdi3.c): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/Makefile
	[$(subdir) = csu] (sysdep_routines): Likewise.
	[$(subdir) = csu] (sysdep-only-routines): Likewise.
	[$(subdir) = csu] (CFLAGS-divdi3.c): Likewise.
	* sysdeps/wordsize-32/Makefile: Remove file.
	* sysdeps/wordsize-32/symbol-hacks.h: Definitions move to ...
	* sysdeps/wordsize-32/divdi3-symbol-hacks.h: ... here.

2 files changed, 4 insertions, 11 deletions

diff --git a/sysdeps/wordsize-32/Makefile b/sysdeps/wordsize-32/Makefile
deleted file mode 100644
index 82beac44ed..0000000000
--- a/sysdeps/wordsize-32/Makefile
+++ /dev/null
@@ -1,7 +0,0 @@
-ifeq ($(subdir),csu)
-ifeq (yes,$(build-shared))
-sysdep_routines += divdi3
-shared-only-routines += divdi3
-CPPFLAGS-divdi3.c = -Din_divdi3_c
-endif
-endif
diff --git a/sysdeps/wordsize-32/symbol-hacks.h b/sysdeps/wordsize-32/divdi3-symbol-hacks.h
index 0aec1e0b97..6c90cb796d 100644
--- a/sysdeps/wordsize-32/symbol-hacks.h
+++ b/sysdeps/wordsize-32/divdi3-symbol-hacks.h
@@ -1,4 +1,4 @@
-/* Hacks needed for symbol manipulation.
+/* Hacks needed for divdi3 symbol manipulation.
    Copyright (C) 2004-2017 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,13 +16,13 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include_next "symbol-hacks.h"
-
 /* A very dirty trick: gcc emits references to __divdi3, __udivdi3,
    __moddi3, and __umoddi3.  These functions are exported and
    therefore we get PLTs.  Unnecessarily so.  Changing gcc is a big
    task which might not be worth it so we play tricks with the
-   assembler.  */
+   assembler.
+   Note: in_divdi3_c is only used to avoid symbol alias on divdi3
+   build itself.  */
 #if !defined __ASSEMBLER__ && !defined in_divdi3_c && IS_IN (libc) && defined SHARED
 asm ("__divdi3 = __divdi3_internal");
 asm ("__udivdi3 = __udivdi3_internal");